286 INSECT TRANSFORMATIONS. 



the mandibles being liorny, jointed, and capable of 

 uniting into one pointed borer. The tail is furnished 

 with plumed bristles, which appear to serve the pur- 

 pose of fins. The nearer this chrystalline larva is to 

 its transformation, the more distinctly may be seen 

 four kidney-shaped transparent bodies, of a brown 

 colour, a pair on the fourth ring from the tail, and 

 another pair at the shoulders. The former, perhaps, 

 serve to inclose the tail fins of the pupa ; the latter 

 the horns of the pupa, which again encase the an- 

 tennae of the gnat ; but in another species (Corethra 

 culiciformis) De Geer supposed these to be respi- 

 ratory organs. We are not aware that this larva has 

 been actually seen to cast its skin, but there can be 

 no doubt of the fact, for Reaumur found exuviae at 

 the bottom of the glasses where he kept them ;* and 

 we are not, consequently, authorized to assert that its 

 transformation is " not efiected, as in other insects, 

 by casting the outer skin, but by an actual conver- 

 sion of one form of matter into another, "f We 

 watched above a hundred of them without being so 

 fortunate as to see their transformation into pupae, 

 though we more than once observed the emergence of 

 the fly. 



Our chief reason, however, for introducing it here, 

 is to show the mode in which the pupa is suspended, 

 or rather buoyed up, in the water, by means of its 

 foliated tail and the shape of its body, which is 

 bulged out above, and narrowed as it approaches the 

 lower extremity. It is, besides, very lively in the 

 pupa state, and jerks about with great agility, but 

 usually keeps close to the surface of the water, so as 

 to project its horns or antennae cases above it. )n 

 the figures we have endeavoured to combine the 

 details of Reaumur and Dr. Goring. 



* Reaumur, vol. v. p. 41-2. 



f Goring and Pritchard, Nat. Hist., No. 1. p. 23, 



